INTERACTION OF A TURBULENT BOUNDARY LAYER WITH A STEP AT M=3
PRINCETON UNIV NJ JAMES FORRESTAL RESEARCH CENTER
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An experimental investigation of the flow over a dimensional step was carried out at M 2.92. The separation of a turbulent boundary layer and the associated shock wave pattern were studied as the step height was varied from 13 to 2 times the boundary layer thickness. The interaction was observed by Schlieren and shadowgraph techniques supplementing the wall static pressure surveys and detailed total head surveys through interaction. Reverse flow regions were investigated by using a tiny total head tube which would face downstream as well as upstream. For all steps tested, separation was detected at a wall static pressure ratio of 2.1. After the separation point the pressure continued to rise, but at a slower rate, to a maximum value which assumed a constant value for the steps which were higher than the boundary layer. For these step heights, the front parts of the interaction were identical. The pressure distribution, the pressure ratio, and location of the separation point, were identical and duplicated the results obtained in the studies of a strong incident shock interacting with a turbulent boundary layer. The occurrence of separation and the initial region of separated flow covering a distance of 6 to 8 boundary layer thicknesses appears to be independent of the cause of separation in spite of the large differences in the flow downstream of this region.
- Fluid Mechanics